Venture-capital giant New Enterprise Associates is on the brink of a comeback, thanks to the huge return it is poised to reap from its investment in the growing coupon site.

Since 2008, NEA has invested about $15 million for a 20 percent stake in Groupon, a person familiar with the firm said. That is small bucks for what could turn into one of the biggest returns in venture-capital history.

Google is in advanced talks to buy Groupon, which offers users daily deals on local businesses, for roughly $5 billion, although the price is “still in flux,” a person close to the talks said. If Groupon seals the deal, it means NEA will walk away with a cool $1 billion — or 66 times its investment.

While other Groupon investors, including Accel Partners, Battery Ventures and Russia’s Digital Sky Technologies, will also see major paydays, NEA will get the sweetest return after participating in three of four funding rounds that raised a total of $171 million.

“This will move the needle,” the source close to NEA said.

Like much of the venture-capital industry, NEA, headed by chairman and co-founder Dick Kramlich, had hit a rough patch. The $15 million Groupon investment was part of a $2.5 billion fund that NEA closed in 2006.

As of March 31, the fund had a value equal to a 5.1 percent net annual return and had returned very little capital to investors. The Groupon investment, however, will change that.

“NEA’s recent funds have not been above the crowd,” the source close to NEA said. “This will raise their profile.”

NEA did not return calls.

The 74-year-old Kramlich has earned this win.

His firm first invested $4.8 million in what became Groupon in early 2008, when the startup was called The Point. At the time, The Point provided a way to organize fund-raisers, rallies and boycotts that needed a set number of people to succeed. Participants acted only once a pre-set tipping point had been reached.

The startup failed, however, and NEA and The Point were forced to rework the business model. They marketed a product to merchants to post coupons that they would honor only after a certain number of clippers had reached a tipping point. This idea formed the basis of what would become Groupon.

NEA invested more to get Groupon off the ground. The company, run by 30-year-old CEO Andrew Mason, grew rapidly and now generates $500 million in revenue, splitting sales with merchants, and roughly $200 million in profit, the source close to NEA said.

The tech giant is interested in Groupon so it can start marketing coupons around the world, the source said. And while the $5 billion price tag is hard to justify based on the company’s current financials, Google would buy Groupon based on what it believes the company will generate down the line.

Google probably also remembers when it could have bought rival Facebook for $1 billion five years ago and does not want to miss another opportunity.

“Google is not planning to do anything with the business model besides greatly expanding the coupon business,” the source said. jkosman@nypost.com